Specifications, Service and Repair of Farm and Lawn Tractors

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Kubota B7800 Troubleshooting

Kubota B7800 Engine Troubleshooting

Engine difficult to start or won't start: Dirty fuel filter. Clean the filter element. Air in fuel tank. Bleed fuel tank. Fuel injection nozzles fault. Install a new kit of correctly balanced nozzles. Fuel injection pump is damaged. Repair or change injection pump.

Engine shuts off while running: Fuel injection pump timing is not adjusted. Adjust fuel injection pump as required. Fuel filter element is dirty. Clean the filter or install new filter element. Engine is not preheated. Warm up the engine.

Diesel starts but immediately shuts off: Fuel filter element is dirty. Clean or change the filter. Fuel injection pump is not working correctly. Repair or install a new fuel pump. Clogged air cleaner. Change air filter element.

Engine overheating: Clogged radiator fins or leaking radiator cap. Install new cap or clean radiator. Insufficient coolant fluid. Refill to the correct level and inspect system for leaks. Fan belt slipping or worn. The fan belt needs to be replaced. Engine oil insufficient. Add oil to the engine crankcase.

Engine power is too low: Damaged or dirty injection nozzles. If necessary, replace with a new nozzle. Clogged fuel lines or hoses. Fuel lines and hoses need to be cleaned. Dirty air cleaner. Clean air cleaner element. Leaking cylinder head gasket. Gasket should be replaced.

Engine noise or knocking: Engine is not fully warmed up. Warm up the engine. Low engine oil level. Need to add engine oil. Fuel injection pump timing is wrong. Set it up as required. Worn or scored pistons. Install new pistons. Connecting rod is not aligned or worn. Need to change or align the connecting rod.

Engine stalls at idle: Improperly adjusted low idle speed. Correct low idle settings. Valve clearance is out of adjustment. Correct valve clearance needs to be set. Fuel injection pump malfunctioning. Rebuild or change fuel pump.

Insufficient oil pressure: Insufficient engine oil. Fill up the engine oil. Oil pump is worn or damaged. Repair or change. Oil filter is dirty. Clean or change engine oil filter.

Kubota B7800 Hydrostatic Transmission Troubleshooting

Excessive hydrostatic transmission noise: Bent or unadjusted speed control pedal linkage. Repair or adjust linkage. Excessive transmission load. Reduce transmission load. Transmission oil is contaminated or oil level is insufficient. Fill to required level or change the transmission oil. Relief valve failure. Replace the valve. Worn or defective transmission components. After disassembling and inspection, change defective components.

Transmission fluid overheating: Transmission overload. Load needs to be reduced. Cooling components are defective or plugged. Check all cooling components and change or repair if required. Transmission fluid level is low. Add fluid to the transmission housing. Transmission fluid filter is clogged. Clean or change transmission fluid filter.

Lack of power: Low fluid level. Need to add transmission fluid. Relief valve is damaged. Change relief valve. Worn or unadjusted speed control linkage. Adjust or replace linkage.

External oil leaks: Clogged oil drain line. Clean or replace drain line. Damaged gaskets or seals. Install new gaskets or seal. High internal transmission housing pressure. Change defective parts.

Kubota B7800 Hydraulic System Troubleshooting

Hydraulic system overheats: Improper type of hydraulic oil. Use the proper type of oil. Contaminated hydraulic oil. Change hydraulic oil. Air trapped in hydraulic system. Bleed air from system. Main relief valve failure. Relief valve replacement required.

Insufficient hydraulic fluid pressure: Low hydraulic oil level. Checking hydraulic oil level and add if necessary. Clogged hydraulic fluid filter. Hydraulic filter maintenance required. Leaks in hydraulic lines. Inspect hydraulic system for leaks and repair it. Hydraulic control valve block is not set properly. Use the proper setting. Hydraulic pump is faulty. Change or repair hydraulic oil pump. Hydraulic cylinder malfunction. Repair or change hydraulic cylinder.

3-point hitch fails to lift or lifts slowly: Hydraulic pump failure. Install a new hydraulic fluid pump. Defective main relief valve. Relief valve must be changed. Defective hydraulic spool valve block. Change or repair hydraulic valve. Broken hydraulic cylinder. Replace or repair hydraulic cylinder. Hydraulic fluid level low. Checking hydraulic fluid level and add if necessary. Hydraulic oil filter element is clogged. Change hydraulic filter element or clean if necessary. Hitch is under excessive load. Reduce the load is required.

Hitch cannot be dropped or dropping is too slow: Hydraulic cylinder failure. Repair or install a new hydraulic cylinder. Incorrect adjusted hydraulic control valve. Adjust correctly. Damaged lift arm shaft. Change the shaft. 3-point hitch is out of adjustment. Adjust three-point hitch as required.

3-point hitch jerks when lower or lift: Hydraulic oil contamination. Change the oil. Hydraulic pump not working. Replace or repair hydraulic oil pump. Air in hydraulic system. Bleed air from hydraulic system. Defective hydraulic spool valve. Repair or change the valve. Faulty hydraulic cylinder. Replace or repair hydraulic cylinder.

Kubota B7800 Steering System Troubleshooting

Excessive steering wheel play: Worn steering column coupling or shaft. Replace defective component. Steering pump not working. Check the steering pump and replace if necessary. Steering linkage assembly is worn or loose. Check and replace as required. Defective or worn steering control valve. Repair or change the steering control valve. Steering box parts have excessive wear. Defective power steering box components must be replaced.

Hard Steering: Air in the hydraulic steering system. Bleed the system of air. Steering filter element is clogged. Change steering filter element. Steering oil level is low. Fill up steering oil to required level. Steering control valve has damage or wear. Inspect and change as required. Steering box parts are faulty. Replace defective components of power steering box. Steering pump not working. Repair or replace steering pump. Faulty or stuck pump flow control valve. Replace or service control valve. Worn or incorrectly fitted steering column. Replace the steering column or refit it correctly. Front tyres are worn unevenly. Install new tyres. Not adjusted toe-in. Adjust toe-in wheels.

Tractor is pulling to right or left: Steering box parts are damaged. Repair power steering box. Steering control valve has damage or wear. Check and replace as required. Incorrect toe-in. Check and adjust toe-in. Loose or worn steering linkage components. Replace or repair steering linkage. Front wheel bearings are worn or incorrectly adjusted. Install new bearings or adjust it correctly. Tire pressure is uneven. Adjust the tire pressure.

Kubota B7800 Electrical System Troubleshooting

Battery does not charge: Corroded or loose electrical wire connections. Tighten or clean connections. Battery terminal clamps are defective. Replace terminal clamps. Battery faulty cell. Install a new battery. Damaged or loose belt. Adjust belt tension or change the belt.

Starter motor turns slow: Low battery output. Recharge the battery. Battery will not hold charge. Service or change the battery. Disconnected wires or corroded battery terminals. Check cable connections and replace or service terminals.

Starter is not cranking: Battery is drained or defective. Recharge or replace battery. Wiring harness is disconnected or improperly connected. Check wiring harness and connect as required. Low battery output. Battery is drained, recharge it. Starter motor is faulty. Repair or change starter.

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